package mcp

import (
	"bufio"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

const tokenFileName = ".tm_token"

// TokenFile holds credentials from a workspace .tm_token file.
type TokenFile struct {
	Project string
	Token   string
	Path    string
}

// FindTokenFile walks from start (usually cwd) upward looking for .tm_token.
func FindTokenFile(start string) (TokenFile, error) {
	dir, err := filepath.Abs(start)
	if err != nil {
		return TokenFile{}, err
	}
	for {
		path := filepath.Join(dir, tokenFileName)
		if st, err := os.Stat(path); err == nil && !st.IsDir() {
			tf, err := ParseTokenFile(path)
			if err != nil {
				return TokenFile{}, err
			}
			return tf, nil
		}
		parent := filepath.Dir(dir)
		if parent == dir {
			break
		}
		dir = parent
	}
	return TokenFile{}, fmt.Errorf("no %s found (create an MCP token in the TUI with g, then place project=… and token=… in %s)", tokenFileName, tokenFileName)
}

// ParseTokenFile reads project= and token= lines from path.
func ParseTokenFile(path string) (TokenFile, error) {
	f, err := os.Open(path)
	if err != nil {
		return TokenFile{}, err
	}
	defer f.Close()

	tf := TokenFile{Path: path}
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		line := strings.TrimSpace(sc.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		key, val, ok := strings.Cut(line, "=")
		if !ok {
			continue
		}
		key = strings.TrimSpace(strings.ToLower(key))
		val = strings.TrimSpace(val)
		switch key {
		case "project":
			tf.Project = val
		case "token":
			tf.Token = val
		}
	}
	if err := sc.Err(); err != nil {
		return TokenFile{}, err
	}
	if tf.Project == "" || tf.Token == "" {
		return TokenFile{}, fmt.Errorf("%s must contain project= and token= lines", path)
	}
	return tf, nil
}